Method of making brake drums



Jan. 9. 1934.

E. G. BUDD METHOD OF MAKING BRAKE DRUMS Original Filed May 5, 1929 FIG. 1.

INVENTOR. EDWARD G. BU DD.

ATTORNE;

Patented Jan. 9, 1934 UNITE rare FlCE Budd Wheel Company, Philadelphia,

Pa, a

corporation of Pennsylvania Application May 3, 1929. Serial No. 360,226 Renewed May 9, 1933.

3 Claims.

The method of my invention relates to brake drums per se and particularly to brake drums formed integrally with hubs or integrally with wheel discs and the like. But even prior to an understanding of the invention, it goes almost without saying that the invention may be applied to the manufacture of all brake drum like structures.

Incident to the keenest of competition among the various manufacturers of motor cars every endeavor is nowadays being made to cheapen production Without impairing quality. Every single part of the automobile is undergoing the closest of study in the course of these efforts.

The wheel has within the past two or three years been given a highly concentrated study. Integral hubs and brake drums have been proposed and integral discs and brake drums, but thus far they have not been adopted in spite of the apparent saving in fabrication and assembly costs incident to the making of the two parts in one integral whole. The economies of production according to the methods proposed before have not been sufiiciently great to bring about commercial adoption. The outstanding aim of my invention is to produce integral brake drum like structures with greatly improved economy.

Subordinate aims of my invention relate to improvement in form and appearance, a special adaptability to integrality of hubs, brake drums and heads per se, to the coincident formation of drum strengthening beads or flanges, and above all of these subordinate objects, the production of a structure whose dimensions can be held most closely to standard, free from irregularities and requiring less machining.

The process of my invention consists in obtuse angled rolling integrally of the head, (this may be the head per se of the drum, the body of an integral disc, or a combined head and integrally rolled hub) together with a drum per se in an intermediate conically shaped form, (the preliminarily shaped drum may or may not include the reinforcements of the drum and in 45 this case does not include the reinforcing bead or flange) and thereafter circumferentially contracting the conically shaped preliminary form of the drum to the cylindrical form desired. (This contracting may or may not include the simultaneous contracting of the reinforcing means of the bead or flange.)

The drawing illustrates the carrying out of my invention in the manufacture of integral p hubs and brake drums.

Figure 1 is an axial cross section of the billet from which the obtuse angled rolling is started.

Figure 2 is an axial cross section of obtuse angled rolling dies and a combined hub and brake drum which has been rolled by the dies according to the method.

Figure 3 illustrates the cross section of drum forming dies which have been utilized to form the drum according to an earlier method, and which may be utilized as a part of my method to give the conical shaped form by obtuse rolling 5 a more acute such shape.

Figure 4. is an axial cross section of the contracting machine dies which have operated upon the structure after the step of Fig. 2 to give the preliminary conical shape of the drum the final cylindrical shape desired.

- Figure 5* is a similar axial section of an expanding machine shown as having operated upon the structure after the step of Figure 4 to expand the cylindrical drum truly to size.

Figure 6 is an axial cross section of the completed structure.

The billet 10 shown in Fig. l is a section of a bar which has been subjected to action in a prepress to form depressions 11 in its ends for the reception of the centering and coring pins 12 of the obtuse angled rolling mill as designated in Fig. 2. The action of the pro-press has produced a bulge in the billet giving its main body in general an oval shape.

Under the action of the obtuse angled dies 13, 14 of Fig. 2 the billet is rolled into a structure comprising a hub 15 and a head 16 each given substantially if not wholly the final form desired in which the flange of the hub and the head 16 may or may not extend truly at right angles to the axis of the hub as illustrated. This rolling operation, however, has but preliminarily shaped the drum 1'? of the structure and the edge bead or flange 18, having given the drum 17 a conical shape and both the drum and bead 18 an oversized diameter.

The obtuseness of the conical form of drum 17 will depend upon the nature of the rolling mill employed. It may be more or less obtuse. If OQ more obtuse than desired, a die stamping operation is resorted to as illustrated in Fig. 3 to decrease the obtuseness of the drum 17. The obtuseness may in this step be carried to the cylindrical form if desired. According to earlier prac- 5 tices by me a die stamping operation was used to entirely form the drum. The initial step was not to pre-form the drum by obtuse angled rolling, but to initially roll the hub 15 and the disc 19 as indicated in dotted lines in Fig. 3, or in other 19 words, to obtuse roll an undersized hub 15 and an oversized head 16. Thereafter by die stamping according to the step of Fig. 3, the outer portion of the head 16, designated as disc 19, I turn downwardly into a cylindrical form. But I prefer wherever the characteristics of the obtuse angle mill will permit to pre-form drum 17 at such acute incidence as will enable me to omit the intermediate step of Fig. 3 and to proceed directly to the step of Fig. 4. In this step the structure as pre-formed in Fig. 2 is placed in a contracting machine of standard make embodying radially inwardly acting dies 20 and circumferentially contracted to the cylindrical form desired but to a less diameter than desired. This contracting operation reduces the coincidence of the drum to a cylindrical form and simultaneously contracts the reinforcing bead 18 by direct engagement of the dies therewith. The reduction of the diameter below the final diameter desired is made just sufficient for efficient expansion to the proper diameter according to the next step of my invention.

This next step as shown in Fig. 5 is the placement of the structure as it leaves the contracting machine of Fig. 4 in an expansion machine com-- prised of radially acting expanding dies 21 which engage the drum from the interior and expand it outwardly precisely to the dimension desired. In so expanding it there may be used coacting exterior resisting dies 22 to appropriately bear upon the head 16 and the bead 18 in a resisting way to preclude irregular or distorting movements. Similarly in connection with the step of Fig. 4 interior resisting dies 23 may be made use of. p

The final product appears in Fig. 6. It is ready for machining. It is true to form. It is true to dimension. It is one integral whole. As a result it requires a veritable minimum of machine work to render it ready for use, and of course, requires no assembly work whatever.

The modifications of which my invention may be found susceptible without departing from its generic spirit are likewise to be protected to me by the annexed claims.

What I claim as new and useful and desire to protect by Letters Patent is:

1. The process of making brake drum like structures which consists in obtuse angled rolling integrally of the head and a conically shaped drum of the structure, radially contracting said conically shaped drum to the cylindrical form desired and to a diameter below the final diameter desired, and thereafter expanding it to the true diameter.

2. The process of making brake drum like structures which consists in obtuse angle rolling an integrally formed head and a conically formed drum of substantially the final form, and thereafter radially contracting said drum by directly applied radial pressure to develop the cylindrical form of the same.

3. The process of forming a metallic structure having an annular head and substantially cylindrical flange, which process comprises obtuse angle rolling an integrally formed head and a l flange of conical shape but of almost the final form, and thereafter exerting pressure radially inwardly against said flange to contract the same and bring it to a cylindrical form.

EDWARD G. BUDD. 

